1. Field of the Invention
The present general inventive concept relates to an apparatus to treat a substrate, and more particularly, to an apparatus to treat a substrate using a ferrite core to improve plasma-generating efficiency.
2. Description of the Related Art
A substrate for a semiconductor wafer or a display apparatus (hereinafter, referred to as “substrate”) is manufactured by performing repeated deposition and etching processes of a thin film.
FIG. 1 is a sectional view illustrating an apparatus to treat a substrate using a ferrite core, and FIG. 2 is a plane view illustrating the apparatus of FIG. 1.
Referring to FIGS. 1 and 2, a conventional apparatus to treat a substrate comprises an upper container 111 and a lower container 112 which are combined with each other. A space formed by both containers 111 and 112 is divided into an upper reaction space 113 and a lower reaction space 114 by partitions 121 and 122. Gas is brought in the reaction spaces 113 and 114 and ionized, thereby generating plasma. An upper chuck 131 is disposed in the upper reaction space 113 and a lower chuck 132 is disposed in the lower reaction space 114. Typically, the substrate to be treated is disposed only on the lower chuck 132. Six toroidal ferrite cores 141 are disposed circularly on the same plane in a middle of both reaction spaces 113 and 114 at a regular interval. A coil 142 winds around each ferrite core 141. The coil 142 winds around adjacent ferrite cores 141 in opposite directions, thereby making phases of an induced electromotive force generated by the adjacent ferrite cores 141 opposite.
Both reaction spaces 113 and 114 communicate with each other through a through hole 152 formed in a tube 151 passing through the center of the ferrite core 141. Reactant gas passes through the through hole 152. The through hole 152 is a passage of a discharging current. When treating the substrate, the coil 142 winding around the ferrite core 141 becomes a primary side and the plasma becomes a secondary side, and accordingly high-frequency electric power applied to the coil 142 is transmitted to the secondary side of the plasma. The phase difference of the induced electromotive force between the adjacent ferrite cores 141 is 180 degrees. The passage of the current induced in the plasma is formed in a closed circuit through two adjacent through holes 152. Arrows in FIG. 1 shows six induced currents formed between the adjacent through holes 152.
In order to improve plasma-generating efficiency, the passage of the secondary current induced in the plasma should be formed in a closed circuit. Therefore, the conventional apparatus for treating the substrate 100 comprises the two reaction spaces 113 and 114. However, only one side of the substrate is treated in the conventional apparatus for treating the substrate 100 while the plasma is generated in both sides of the substrate, thereby reducing density and efficiency of the plasma.